Room temperature-curable, heat-conductive silicone rubber composition

Abstract

Provided is a room temperature-curable, heat-conductive silicone rubber composition, including: (A) a diorganopolysiloxane with both molecular chain terminals blocked with hydroxyl groups and/or organooxy groups, (B) a heat-conductive filler other than a palladium powder, (C) an organosilane containing two or more hydrolyzable groups, and/or a partial hydrolysis-condensation product thereof, and (D) a palladium powder. The composition improves on the drawbacks of the conventional technology, is able to suppress the quantity of hydrogen gas produced from the heat-conductive filler, exhibits superior storage properties, and yields a low-hardness cured product upon curing. The cured product is useful as a heat-conductive material for a heat-generating electronic component.

1. A room temperature-curable, heat-conductive silicone rubber composition, comprising:
 (A) 100 parts by mass of an organopolysiloxane represented by a general formula (1) shown below: 
 
       
         
           
           
               
               
           
         
       
       wherein, each R 1  represents, independently, a hydrogen atom, or an unsubstituted or substituted monovalent hydrocarbon group, R 2  represents identical or different, unsubstituted or substituted monovalent hydrocarbon groups, each Z represents, independently, an oxygen atom or a bivalent hydrocarbon group, a represents 0, 1 or 2, and n represents an integer of 10 or greater,
 (B) 10 to 4,000 parts by mass of aluminum powder, 
 (C) 1 to 50 parts by mass of an organosilicon compound represented by a general formula (2) shown below:
   R 3   b SiX 4-b    (2) 
 
 
       (wherein, R 3  represents an unsubstituted or substituted monovalent hydrocarbon group, X represents identical or different hydrolyzable groups, b represents 0, 1 or 2, and when b=2, the R 3  groups may be identical or different, and/or a partial hydrolysis-condensation product thereof, and
 (D) 0.01 to 1.0 parts by mass of a palladium powder per 100 parts by mass of the aluminum powder. 
 
     
     
       2. The room temperature-curable, heat-conductive silicone rubber composition according to  claim 1 , wherein the composition is a one-part type composition. 
     
     
       3. The room temperature-curable, heat conductive silicone rubber composition according to  claim 1 , wherein R 1  of formula (1) is hydrogen. 
     
     
       4. The room temperature-curable, heat conductive silicone rubber composition according to  claim 1 , wherein the shape of particles of the aluminum powder is scale-like. 
     
     
       5. The room temperature-curable, heat conductive silicone rubber composition according to  claim 1 , wherein R 2  of formula (1) is methyl. 
     
     
       6. The room temperature-curable, heat conductive silicone rubber composition according to  claim 1 , wherein Z of formula (1) is oxygen or ethylene. 
     
     
       7. The room temperature-curable, heat conductive silicone rubber composition according to  claim 1 , wherein a viscosity at 23° C. of the organopolysiloxane represented by the general formula (1) is in a range from 500 to 200,000 mPa·s. 
     
     
       8. The room temperature-curable, heat conductive silicone rubber composition according to  claim 1 , wherein an average particle size of the aluminum powder is in the range from 0.1 to 70 μm. 
     
     
       9. The room temperature-curable, heat conductive silicone rubber according to  claim 4 , wherein an average particle size of the aluminum powder is in the range from 0.1 to 70 μm. 
     
     
       10. The room temperature-curable, heat conductive silicone rubber composition according to  claim 1 , further comprising at least one filler selected from the group consisting of a metal oxide, a metal carbonate, glass wool, carbon black, fine mica powder, fused silica powder and a powder of a synthetic resin. 
     
     
       11. The room temperature-curable, heat conductive silicone rubber composition according to  claim 1 , further comprising an additive selected from the group consisting of an adhesion assistant, a pigment, a dye, an age resistor, an antioxidant, an antistatic agent, a flame retardant, a thixotropic improver, and an antibacterial agent. 
     
     
       12. A cured product obtained by curing the composition according to  claim 1 . 
     
     
       13. A method for conducting heat away from a heat-generating electronic component to a heat-dissipating member, comprising sandwiching the cured product according to  claim 12  between the heat-generating electronic component and the heat-dissipating member. 
     
     
       14. An electronic device comprising:
 a heat-generating electronic component, 
 a heat-dissipating member, and 
 the cured product according to  claim 12  wherein the cured product is sandwiched between the heat-generating electronic component and the heat-dissipating member.